Inductance corrector



Jan.

Filed Feb. 29, 1952 INVENTOR. 1E0 K Mil-FL! 47* roam/[r United States Patent 2,731,608 INDUCTANCE CORRECTOR Leo V. Mifllin, Cedar Rapids, Iowa, assignor to Collins Rfagio Company, Cedar Rapids, Iowa, a corporation 0 owa Application February 29, 1952, Serial No. 274,211 4 Claims. (Cl. 336-13i)) This invention relates in general to a variable inductance means and in particular to an apparatus which can automatically be adjusted to conform to a desired tuning characteristic.

It is oftentimes necessary to obtain a variable inductance which has a shaft versus tuning characteristic that is controllable. In a core tuned inductor it is normally impractical to obtain the desired tuning characteristic by winding the coil with a variable pitch or by cutting a variable pitch into the lead screw which moves the core.

It is an object of this invention to provide an inductance adjusting means so that the tuning characteristic of a slug tuned coil may be controlled in the desired manner.

Another object of this invention is to provide a variable inductance wherein a mass of core material is mounted on a pivoted lever arm adjacent the inductance coil and rides on a cam surface which moves it relative to the coil to attain the desired inductance characteristic.

Further objects, features and advantages of this invention will become apparent from the following description and claims when read in view of the drawings, in which:

Figure 1 is a top view of the variable inductance means of this invention.

Figure 2 is a partial section side view taken on line 22 of Figure l and,

Figure 3 is a detailed view illustrating the cam follower mechanism.

Figure 1 illustrates a pair of end plates and 11 which rotatably support a tuning shaft 13. The tuning shaft has a tuning knob 14 attached to one end thereof. A hollow coil form 16 is attached to the plate 10 and has a winding 17 formed thereabout.

An inductance core 18 has an inner threaded portion 19 which is threadedly mounted on tuning shaft 13. As best shown in Figure 2, core 18 has an outer portion formed of a suitable magnetic material, as for example, pressed iron. The inductance of coil 17 is varied as the core 18 is moved longitudinally thercthrough.

The shaft rotation versus core travel characteristic of the apparatus thus far described might not be the desired characteristicv So as to adjust this characteristic a guide member 22 is mounted between the plates 10 and 11 and has attached thereto a cam surface 23. The core 18 has a bifurcated portion 24 attached to it and each of the legs 26 and 27 has a roller 23 and 29, respectively, attached thereto and engageable with the uide 22 on opposite sides thereof.

A lever arm 31 is attached to the member 24 and is spring loaded so as to always pivot away from the core 18. The end 32 of the lever arm 31 forms a cam engaging portion. Attached to the rear of the cam engaging portion 31 is a mass 33 of cot-rector core material which might be, for example, pressed powdered iron. The movement of the mass 33 relative to the coil 17 varies the external reluctance path and consequently, the inductance.

The cam 23 is formed so that the distance between the mass 33 and the coil 17 is such as to attain the desired correction.

Thus, a coil and slug may have its characteristic ad justed merely by varying the shape of the cam 23. This allows coils and slugs to be mass produced and individually corrected or changed to a desired characteristic merely by cutting cam 23.

It is seen that this invention provides a simple and inexpensive manner for controlling the inductance of a slug tuned coil.

Although this invention has been described with respect to particular embodiments thereof, it is not to be so limited as changes and modifications may be made therein which are within the full intended scope of the invention as defined by the appended claims.

What is claimed is:

1. Apparatus for controlling the tuning characteristic of a slug-tuned coil comprising, a pair of end plates, guide means connecting said end plates, a tuning shaft rotatably supported between said end plates, a hollow coil form mounted to one of said end plates and concentric about said tuning shaft, a slug threadedly received on the portion of said tuning shaft between said end plates, a bifurcated portion attached to one end of said tuning slug and engageable with said guide, a cam surface attached to said guide, a lever arm attached to said bifurcated member and engaging said cam surface, and a mass of core material mounted on said lever arm and supported adjacent to and external of said coil.

2. Means for controlling the tuning characteristic of a slug-tuned coil comprising, a pair of end plates, a hollow coil form mounted to one of said end plates, a coil formed about said coil form, a tuning shaft rotatably supported between said end plates and passing through said coil form, a tuning slug threadedly received on said tuning shaft, a guide member mounted between said end plates, 21 bifurcated portion attached to said slug and en gageable with either side of said guide, a lever arm at tached to said bifurcated portion, a cam surface attached to said guide and engageable with the free end of said lever arm, and a mass of core material mounted to said lever arm and supported adjacent to and external of said coil.

3. Apparatus for varying the inductance of a coil comprising, a base plate, said coil mounted to said base plate, a tuning shaft rotatably supported in said base plate, a powdered iron core slug threadedly mounted on said tuning shaft and receivable within said coil, a guide extending from said base plate, a bifurcated portion attached to one end of said slug and engageable with said guide, a cam portion mounted to said guide, a lever arm attached to said bifurcated portion and engageable with said cam surface, and a mass of core material mounted adjacent the end of said lever arm so as to move it longitudinally and transversely of said coil.

4. A variable inductance comprising a coil, a tuning shaft extending axially of said coil, a main tuning slug in threaded engagement with said shaft and movable axially within said coil by rotation of said shaft, a corrector slug adjacent and exterior of said coil, a cam surface extending axially of said coil, a cam follower movable laterally of said coil engaging said cam surface and supporting said corrector slug, means for producing relative motion in a direction axially of said coil between said cam surface and said cam follower to displace said Corrector slug laterally of said coil, said means being drivingly connected to said shaft whereby the position of said corrector slug is a function of the shaft rotation.

References Cited in the file of this patent UNITED STATES PATENTS 2,340,749 Harvey Feb. 1, 1944 2,468,071 Hunter Apr. 26, 1949 2,505,791 Rennick May 2, 1950 2,598,467 Van Yzeren May 27, 1952 

